Hands-On High Performance with Spring 5

The @Autowired annotation

The @Autowired annotation injects object dependency implicitly. We can use the @Autowired annotation on a constructor-setter-and field-based dependency pattern. The @Autowired annotation indicates that auto wiring should be performed for this bean.

Let's look at an example of using the @Autowired annotation on a constructor-based dependency:

public class BankingService {    private CustomerService customerService;    @Autowired  public BankingService(CustomerService customerService) {    this.customerService = customerService;  }  ......}

In the previous example, we have BankingService that has a dependency of CustomerService. Its constructor is annotated with @Autowired, indicating that Spring instantiates the BankingService ...